Among methods for producing norborneol, the following chemical synthesis method is known: Norbornane as starting material is reacted with an organic acid to form an ester of norbornane; and then, this ester is chemically deacetylated to obtain norborneol. According to such a chemical synthesis method, four kinds of stereoisomers ((+, -)-(endo, exo)-norborneol) are generated, so that complicated purification steps are required for obtaining optically active norborneol by chemical synthesis.
As a method for biologically producing norborneol, the following method is known: An ester of norbornane is brought into contact with a microorganism or reacted with an enzyme and the ester is hydrolyzed. In recent years, Th. Oberhauser et. al. reported a method for producing (-)-norborneol from (+)-norbornyl acetate by using lipass derived from Candida cylindraceae (Th. Oberhauser et. al., Tetrahedron, 43, 3931-3944 1987). Moreover, Oritani et. al. reported a method for producing (-)bornsol and (-)isoborneol from (.+-.)bornyl acetate and (.+-.)isobornyl acetate by using a culture of Trichoderma sp, Trichoderma koningi, Bacillus subtilis var. Niger, and Absidia hyalospora (T. Oritani et. al., Agr. Biol. Chemo, 38(10), 1961-1964, 1974). However, the reactions have low selectivity and thus obtained products have low optical purity. Japanese Laid-Open Patent Publication No. 2-273196 discloses an optical resolution method in which an inhibitor, for selectively inhibiting the reaction of one of the enantiomers by a biological catalyst, resolves a racemic compound. This method can be used for preparing optically active norborneol. However, this method has the following disadvantages: screening is required in order to obtain an inhibitor effective for the selection of optically active norborneol; and an inhibitor should be removed in the course of purification after the reaction, thus complicated manipulation is required. In view of these circumstances, there has been a demand for an improved biological method for obtaining optically active norborneol, in which an ester is brought into contact with a microorganism or enzyme with high stereoselectivity in the course of the hydrolysis of the ester.